The present invention relates to a bond head adapted for use in mounting semiconductor chips or components to substrates and, more particularly, to a bond head equipped with air bearings for enhancing its precision.
Semiconductor chip mounting apparatus typically has an upper chuck and/or a lower chuck for mounting semiconductor chips or components to substrates. More particularly, the upper chuck is typically adapted to pick up a semiconductor chip and to position same in proper orientation relative to a substrate placed on the lower chuck. After proper alignment, the upper chuck moves toward the lower chuck for placing and/or bonding the semiconductor chip to the substrate. The upper chuck and/or the lower chuck are typically equipped with mechanical bearings for permitting relative movement of its components (see, e.g., U.S. Pat. No. 4,899,921). The use of these mechanical bearings can compromise the high precision/accuracy required for mounting/bonding semiconductor chips to substrates.
U.S. Pat. No. 5,308,132 relates to a circuit assembly device having an end effector for picking and placing component parts. The end effector is equipped with a piston movably coupled to an air bearing. Similarly, U.S. Pat. No. 5,600,189 discloses a machine for picking up, holding, moving and positioning electronic components to a printed circuit board. The machine includes an electromagnetic actuator equipped with an air bearing. While the devices disclosed in these patents are equipped with air bearings, they are not adapted for precise and accurate mounting of semiconductor chips to substrates.
The present invention overcomes the disadvantages and shortcomings of the prior art discussed above by providing a new and improved device adapted for mounting semiconductor components to substrates. More particularly, the device includes a housing and a first member rotatably mounted to the housing. A first interface is formed between the first member and the housing. The device also has a second member mounted in the first member. The second member is movable in an axial direction relative to the first member between a first position, in which the second member extends from the first member, and a second position, in which the second member is retracted from the first position. The second member has an engaging mechanism at an end thereof for engaging a semiconductor component when the second member is in its first position. A second interface is formed between the first and second members. The device is also provided with a supplying mechanism for supplying pressurized air to the first and second interfaces so as to form a first air bearing at the first interface and a second air bearing at the second interface. The first air bearing is sized and shaped so as to permit substantially frictionless rotational movement of the first member relative to the housing, while the second air bearing is sized and shaped so as to permit substantially frictionless rectilinear movement of the second member relative to the first member.